1. Field of the Invention
This invention relates to conveying and storage systems. In particular, the invention relates to the conveyance and storage of food products, although it is not necessarily limited to this field of activity. The invention is especially directed to systems suited to the treatment, with temporary storage, of food products, although again the invention is not necessarily limited to this field of application.
2. Description of the Prior Art
In the manufacture and processing of food products, transfer of products from one manufacturing stage to another necessarily involves a conveying system. In order to facilitate flexibility in the manufacturing process and frequently also to allow of environmental treatment of the product, a conveyance system of this kind may also include a storage region in the form of a chamber, which may or may not involve a environmental treatment step, such as cooling or heat treatment. The chamber thus defines a storage region, and optionally also a treatment stage of the processing or manufacturing operation.
The procedures involved in the manufacture and processing of food products may also include placement of food product, typically carried on trays, into an environmental treatment chamber, for temporary storage and subjection to controlled environmental conditions, such as cooling or heat treatment, to either inhibit or accelerate certain changes in the food product. A chamber of this kind thus defines a storage region, and typically also defines a treatment stage of a food processing or manufacturing operation.
Hygiene represents a significant problem in the provision of conveying and storage systems of the foregoing kind in the food processing industry. Conveyors conventionally involve either chain drive of conveying elements such as trays, or alternatively a ratchet type drive. In either circumstance, a multiplicity of moving parts must be provided to advance the food product, however supported, and the cleaning of these moving parts when located within a closed chamber represents a significant and substantial problem, as also does ensuring as far as possible that the moving parts remain free from unwanted and offensive material.
Since hygiene is of great importance in any food processing activity, closed treatment chambers of the foregoing kind for food products must be cleaned at regular intervals, in common with all food handling equipment. For this purpose, it has been the practice to clear the chamber of all product trays, which are held under ambient conditions while the cleaning procedure takes place. Thus a necessary preliminary step in any cleaning operation is to clear the storage chamber of all of the trays within it. The trays may be either placed on the floor of the premises, or alternatively, additional storage accommodation is required to hold them during the cleaning operation in the storage chamber. In either circumstances, substantial handling and space requirements prevail.
There is known a multiplicity of diverse conveying and transfer equipment, among which U.S. Pat. No. 4,475,642 relates to a system for conveying work carriers by means of engagement of driving gears provided along the sides of a path of advance for the carriers with teeth provided on the sides of the work carriers. The system described may include buffer units for intermediate storage and a variety of other features said to offer flexibility in use of the system. However, the need to provide drive gears along the length of the conveying or work carrier transfer system may render an arrangement of this kind inappropriate for a food product environment.
U.S. Pat. No. 5,012,917 discloses a transport apparatus for an assembly line for the conveyance of objects such as motor vehicle bodies. This transport apparatus includes a plurality of movable platforms positioned in end to end contact with one another. Application of a pushing force to one of the platforms by means of a drive mechanism results in this force being applied in turn to the remainder of the platforms, by virtue of their end to end engagement, thus causing them to move along the assembly line. A preferred arrangement described in this specification provides for the platforms to be carried on support rollers and driven by frictional engagement of drive wheels against side members of the platforms. End to end engagement takes place between transverse cross members of the platforms so that each front edge of a platform is engaged against the rear edge of a platform ahead of it in the succession of platforms defining the assembly line. The preferred arrangement provided for guiding the platforms during their forward movement consists of engagement of vertical axis guide rollers on the underside of the platforms against the sides of the upright central member of an inverted T-section guide rail.
A broadly similar apparatus is provided by the disclosure of U.S. Pat. No. 2,999,579. In the system described, a plurality of pallet carriers is mounted for movement along a path defined by supporting members. Each pallet carrier consists of a square block of metal having a continuous channel formed in its side edges for cooperation with guide rails extending along the sides of the path of advance of the carriers. Each of these guide rails has a laterally projecting tongue for reception in a respective channel of the pallet carrier. The pallet carriers are engaged edge to edge so that any pushing movement imparted to any of the pallet carriers will be transmitted to the remainder of the pallet carriers ahead of it arranged in edge to edge juxtaposition or engagement. A transfer device thus serves to advance all of the pallets of a sequence of pallet carriers by virtue of imparting movement to the endmost pallet of the sequence, to thereby advance the remainder of the pallets in edge to edge engagement.
In systems of the foregoing kind, the work carrying units can only be advanced in a forward direction by pushing action, since there is no positive coupling together of the pallet carriers or like units. U.S. Pat. No. 3,703,870 describes however a cargo-pallet coupler mechanism for interconnecting and thereby joining together a series of cargo-carrying pallets or containers. The coupler mechanism consists of a pair of elongated coupler rods, for use one on each side of the interface region between two pallets to be connected together. Each coupler rod has a depending key element at each of its ends for respective engagement in a corresponding pair of block elements affixed one to each pallet or container in the vicinity of the interconnecting region between the pallets, and on their side edges. The coupler mechanism thus provides a bridging bar to interconnect two pallets along their side edges, across the transverse ends of the pallets which are in face to face abutment. Two coupling links are used, one on each side edge of the pallets in their abutment region. The mechanism described is especially applicable to pallets or the like for loading in airplanes and facilitates fast removal in particular of such units from the interior of a cargo aircraft. The coupler mechanism requires however the manual placement of independent elements to interconnect pallets to be coupled together. Moreover, an interconnecting coupler unit is required on each side of each pair of pallets to be connected together.